This invention relates generally to cable closures and more particularly to a novel and improved device for relieving strain on the cables enclosed within such closures.
Cable closures are used in the telecommunications industry for a broad variety of purposes. Generally speaking, such closures are used for terminating or bringing out selected wire pairs from a cable to one or more terminal blocks within the closure. In a telephone cable, such a closure may be provided at the point where one or more pairs on the cable are spliced to the pairs connected to a subscriber.
One particularly advantageous type of closure is generally known as the ready access type and is illustrated for example in U.S. Pat. Nos. 3,153,693 to Baxter et al, issued Oct. 20, 1964, and 3,846,575 to Troy, issued Nov. 5, 1974. In these types of closures, the telephone cables enter and leave through tapered guide members generally known in the art as nozzles. Suitable insulating tape is wrapped around the end of each nozzle to form a waterproof seal. Such closures also receive therethrough a so-called messenger cable which acts as a structural support member for the telephone cable. Additionally, such closures also generally include gripping clamp-like or bracket members for grippingly engaging both the messenger cable and telephone cable to properly maintain the position of the latter relative to the former within the closure.
Such ready access closures have heretofore been used primarily in connection with telephone cables carrying only voice communications. However, it is now becoming more common for such closures to be utilized in connection with cables for carrying electronic data communications or television signals. For such signals, the continuity and integrity of the grounding shield of the cable is quite important.
In this latter regard, it has been found that the strain or pull-out forces experienced at the respective ends of cables entering the closure often causes these cables gradually to work out of the gripping clamps or brackets. It should be recognized that the exterior grounding shield is generally removed from the cable within the closure to permit access to the line pairs to be brought out in the closure. Accordingly, suitable terminal clips or other devices are utilized to grip the severed grounding shield at either end of the cable and a jumper wire or cable used to carry the ground across the closure. However, upon such slipping of the cables relative to the clamps, the continuity of this ground is often disrupted. Moreover, the cable ends may actually come out of the nozzle, thereby breaking the waterproof seal.
It is therefore desirable that the strain on the cable be relieved. It is also desirable that such strain relief be provided in such a manner that the insulation on the cable pairs is not damaged and, particularly, such that the grounding shield and line pairs themselves within the cable are not damaged. Hence, while placing a hose clamp or similar clamping device over the nozzle may provide some strain relief, over-tightening of such clamps can cause undesired damage to the various parts of the cable. Such damage may seriously compromise the ability of the cable to properly carry electronic data communications or television signal.
Moreover, it is desirable that any strain relief arrangement provided can be relatively simply and inexpensively retrofitted on existing installations.